Electromagnetic voltage transformer error optimization analysis method

Abstract

The invention discloses an electromagnetic voltage transformer error optimization analysis method, which comprises the following steps of: 1, expressing PT (potential transformer) load error characteristics as a complex number, and expressing a load complex error vector distribution area by a complex error vector circle according to the load characteristics in a complex number rectangular coordinate system; step 2, carrying out intuitive graphical analysis on PT load error and synthetic error characteristics according to the complex error vector circle; and step 3, based on the error relation shown by the complex error vector circle diagram, adjusting the PT ratio error, the angle difference proportion and the polarity, so that the electric energy metering error caused by the PT error is minimum. According to the complex error vector circle graphic analysis method, the PT ratio error, the size of the angle difference and the positive and negative change rule can be visually displayed, the PT ratio error and angle difference ratio and polarity adjustment are achieved, therefore, the comprehensive error of a corresponding metering electric energy device is minimum, and fairness and justice of electric energy metering are achieved.

Description

Technical Field

[0001] The invention relates to an electromagnetic voltage transformer error analysis and optimization method, belonging to the technical field of electric power measurement. Background Art

[0002] An electromagnetic voltage transformer (PT) is a special transformer that converts the primary high voltage of the power grid into a secondary low voltage in proportion through electromagnetic induction and transmits signals to measuring instruments. It is one of the important devices that make up the electric energy metering device. The accuracy of the electric energy metering device is directly related to the economic interests of both parties to the electric energy transaction, the fairness and justice of the transaction, and the social benefits.

[0003] Voltage transformers are measuring instruments with measurement errors. The magnitude of the error is related to manufacturing factors, operating electrical parameters, and the characteristics of the load connected to the secondary circuit. When the transformer leaves the factory and is installed on site, the only controllable error during operation is the load-related error. The relationship between the electric energy metering error caused by PT error is shown in formula (1). During PT operation, by compensating, adjusting, and matching the parameters related to the secondary circuit load, the PT secondary load is optimized to make the PT operate at the optimal error point of electric energy, which can minimize the electric energy metering error and make the electric energy metering more accurate. For this reason, it is necessary to analyze the PT error characteristics to provide a basis for the allocation and reduction of the ratio difference and angle difference of the PT error. At present, the analysis of PT error is mostly based on its voltage phasor diagram, which only represents the phase relationship of the input and output electrical parameters, as shown in Figure 1. Error analysis using voltage phasor diagrams and geometric relationships is not comprehensive and intuitive, and the PT error characteristics are difficult to express.

[0004]

[0005] Where: is the PT electric energy error; They are the PT ratio differences of phases A, B and C respectively; They are the PT angle differences of the three phases A, B and C respectively; It is the load power factor angle of the PT operating line. Summary of the invention

[0006] The technical problem to be solved by the present invention is: how to analyze and optimize the size ratio and polarity of the corresponding PT ratio difference and angle difference through the PT complex error vector circle to minimize the error of the corresponding electric energy metering device.

[0007] In order to solve the above technical problems, the present invention provides an electromagnetic voltage transformer error optimization analysis method, comprising the following steps:

[0008] Step 1: Express the PT load error characteristics as a complex number. The corresponding polar coordinate and rectangular coordinate expressions are: ;

[0009] in, is the PT load complex error, is the modulus of the PT load complex error; They are the PT secondary circuit load admittance and the impedance angle corresponding to the admittance; They are the PT primary short-circuit converted impedance and the corresponding impedance angle; Admittance , short circuit impedance Model; They are the ratio difference and angle difference of PT load error respectively;

[0010] In the complex plane rectangular coordinate system, according to the load characteristics, the load complex error vector distribution area is represented by a complex error vector circle, and the diameter of the circle is equal to , secondary circuit admittance value Size determines the size of the circle;

[0011] Step 2, perform intuitive graphical analysis of PT load error and synthetic error characteristics based on the complex error vector circle;

[0012] Step 3, based on the error relationship shown in the complex error vector circle diagram, by adjusting the PT load impedance angle, the algebraic sum of the ratio difference / angle difference of the three-phase PT complex errors constituting the electric energy metering device is minimized.

[0013] 2. The electromagnetic voltage transformer error optimization analysis method according to claim 1 is characterized in that: in step 1, according to the load impedance angle variation range of -90°~90°, the PT load complex error is distributed in ~ The 180° semicircular sector area includes quadrants II, III, and IV;

[0014] The 1 / 2 dividing line of the semicircular sector corresponds to the impedance angle =0, that is, the complex error vector of pure resistive load; within the 90° clockwise direction of the dividing line is the inductive load complex error area, accounting for 1 / 2 of the semicircle, including quadrants III and II; within the 90° counterclockwise direction of the dividing line is the capacitive load complex error area, accounting for 1 / 2 of the semicircle, including quadrants III and IV.

[0015] The 1 / 2 dividing line of the semicircular sector corresponds to the impedance angle =0, that is, the complex error vector of pure resistive load; within the 90° clockwise direction of the dividing line is the inductive load complex error area, accounting for 1 / 2 of the semicircle, including quadrants III and II; within the 90° counterclockwise direction of the dividing line is the capacitive load complex error area, accounting for 1 / 2 of the semicircle, including quadrants III and IV.

[0016] In the above-mentioned electromagnetic voltage transformer error optimization analysis method, in step 2, an equivalent transformation is performed on the load complex error:

[0017]

[0018] in Defined as the unit load complex error, corresponding to unit impedance That is, the admittance value is 1 and the impedance angle is The load complex error, that is, the PT load complex error It is the product of the PT load admittance value and the unit load complex error;

[0019] Complex error vector circle based on unit load:

[0020] For resistive loads, the impedance angle =0°, the complex error vector is in the third quadrant, corresponding to the dividing line of the semicircular sector area, that is, the dividing line between the inductive load error and the capacitive load error area; the PT ratio difference and angle difference are always negative and are both constant values;

[0021] For inductive loads, From 0 to 90° in the clockwise direction, the complex error vector is distributed in quadrants III and II, the PT ratio difference is always negative, and the ratio difference changes from "small negative → large negative → maximum negative → small negative", and the maximum ratio difference corresponds to the impedance angle ,and Axis coincidence; PT angle difference can be positive or negative, is the dividing point between positive and negative angle difference, Less than Negative, greater than is positive; the angular difference changes monotonically from “negative large → negative small → 0 → positive small → positive large”, that is, the algebraic value changes monotonically from small to large;

[0022] For capacitive loads, From 0 to -90° in the counterclockwise direction, the complex error vector is distributed in quadrants III and IV, the PT angle difference is always negative, and the angle difference changes from "small negative → large negative → maximum negative → small negative", and the maximum angle difference corresponds to the impedance angle ,and Axis coincidence; PT ratio difference can be positive or negative, is the dividing point between positive and negative ratio difference, Greater than The ratio difference is negative, less than The ratio difference is positive; the ratio difference value changes monotonically from “negative large → negative small → 0 → positive small → positive large”, that is, the algebraic value changes monotonically from small to large.

[0023] In the above-mentioned electromagnetic voltage transformer error optimization analysis method, in step 2, the PT no-load complex error is equivalent to a fixed value inductive load complex error, and the corresponding ratio difference is , the angular difference is , then the ratio difference and angular difference of the synthetic complex error can be regarded as the result of the ratio difference and angular difference of the load complex error after the displacement of the origin of the coordinate system. The coordinate value of the origin movement is , then the synthetic complex error vector circle is an eccentric circle, and the variation law of the ratio difference and angle difference of the synthetic complex error is the same as that of the load complex error;

[0024] For the synthetic complex error:

[0025]

[0026] The magnitude of the vector circle from the origin is:

[0027]

[0028] The error margins of resistance, inductance, and capacitance are:

[0029] .

[0030] Where: They are the error amplitudes corresponding to pure resistance, pure inductance, and pure capacitance loads, that is, the error boundaries of each load characteristic.

[0031] In the above-mentioned electromagnetic voltage transformer error optimization analysis method, in step 3, for the PTs constituting the three-phase four-wire electric energy metering device, when the ratio differences of the three-phase PTs are all of the same sign, the respective complex error vectors are adjusted to The axes are brought closer together, so that the ratio difference tends to 0, and thus the algebraic sum of the three-phase ratio differences tends to 0; when the ratio differences of the three-phase PTs are not all of the same sign, fix one phase and adjust the complex error impedance angles of the other two phases so that the ratio difference of the complex error of one phase is equal to the fixed ratio difference in polarity, and the complex error of the other phase is equal to As the axes approach each other, the ratio difference tends to 0, and finally the algebraic sum of the three ratio differences tends to 0.

[0032] In the above-mentioned electromagnetic voltage transformer error optimization analysis method, in step 3, for the three-phase three-wire electric energy metering device PT, when the ratio differences of the two-phase PTs are of the same sign, adjust the respective complex error vectors to When the axes are close to each other, the angle difference is of the same sign, the ratio difference tends to 0, and thus the algebraic sum of the two phase differences tends to 0; when the ratio difference of the two-phase PT is not of the same sign, fix one phase and adjust the complex error impedance angle of the other phase to make the ratio difference polarity equal to the fixed ratio difference, so that the sum of the two phase differences is equal to 0 and the angle difference is relatively reduced, or adjust the complex error impedance angle of the other phase to be the same as the angle difference of the fixed phase, so that the difference of the two phase angle differences is equal to 0 and the sum of the ratio differences is relatively reduced.

[0033] In the above-mentioned electromagnetic voltage transformer error optimization analysis method, in step 3, the impedance angle is calculated, including:

[0034] a) Knowing the synthetic complex error and no-load error, adjust the error vector circle Impedance angle calculation for close axes

[0035]

[0036] In the formula Indicates the derivation process.

[0037] b) Knowing the synthetic complex error and no-load error, adjusting the difference between the fixed complex error and the fixed complex error Calculation of impedance angles that are different and equal

[0038]

[0039] Respectively represent the composite ratio difference, angle difference and corresponding no-load ratio, angle difference and load ratio, angle difference values ​​to be adjusted; are the adjusted / reference ratio differences, respectively; They are the leakage impedance angle, short-circuit impedance angle, and core hysteresis loss angle of the PT primary winding respectively; is the adjusted target impedance angle.

[0040] In the above-mentioned electromagnetic voltage transformer error optimization analysis method, in step 3, the impedance angle is adjusted and parameter calculation is performed, including:

[0041] a) Negative adjustment and calculation of impedance angle

[0042] For PT secondary resistive load, connect capacitor in series:

[0043]

[0044] That is, the secondary resistive load of the PT A capacitor in series is or capacitive reactance equals Capacitance;

[0045] Connect capacitor in series with PT secondary inductive load:

[0046]

[0047] That is, the secondary inductive load of PT A compensation capacitor is connected in series or Capacitive Reactance Capacitance;

[0048] Connect compensation capacitor in series with PT secondary capacitive load:

[0049]

[0050] That is, the secondary capacitive load of PT A compensation capacitor is connected in series. or capacitive reactance equals of capacitance.

[0051] In the above-mentioned electromagnetic voltage transformer error optimization analysis method, in step 3, b) the impedance angle is adjusted in the positive direction:

[0052] Series compensation inductance for PT secondary capacitive load:

[0053]

[0054] That is, the secondary capacitive load of PT A compensation inductor is connected in series. or inductive reactance equals inductor components.

[0055] They are the PT secondary inductive and capacitive load impedance and the corresponding resistance value, inductive reactance value / compensated inductive reactance value, and capacitive reactance value / compensated capacitive reactance value; They are respectively the compensation capacitance value, inductance value, and CPT working voltage power frequency value.

[0056] Beneficial effects achieved by the present invention: The electromagnetic voltage transformer error optimization analysis method of the present invention can realize a comprehensive and intuitive analysis of the characteristics and change laws of the PT errors generated by different types of loads through the complex error vector circle; the error size corresponds to the circle size, the ratio difference size corresponds to the length of the X-axis projection, and the angle difference size corresponds to the length of the Y-axis projection. The complex error vector circle graphic analysis method can intuitively display the PT ratio difference, angle difference size, positive and negative change laws, and is simple to analyze errors with high accuracy. It is an effective tool for error analysis and optimization, and can realize the scientific adjustment of the PT ratio difference and angle difference ratio and polarity, so as to minimize the comprehensive error of the corresponding metered electric energy device and realize the fairness and justice of electric energy metering. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1a It is the PT equivalent loop diagram in the prior art;

[0058] Figure 1b It is the PT phasor diagram in the prior art;

[0059] Figure 2 is the PT equivalent circuit diagram;

[0060] Figure 3 is a schematic diagram of the PT load complex error vector circle and complex error decomposition;

[0061] FIG4 is a schematic diagram of the PT synthetic complex error vector circle and complex error decomposition;

[0062] FIG5 is a diagram showing the relationship between the ratio difference and the angle difference of the PT unit complex error vector circle. DETAILED DESCRIPTION

[0063] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0064] The principle analysis of the electromagnetic voltage transformer error analysis method of the present invention is as follows:

[0065] Figure 2 middle, They are the leakage impedance of the primary and secondary windings of the PT respectively;

[0066] for Converted to the equivalent leakage impedance of the primary winding, ;

[0067] are the secondary load admittance and the primary admittance converted to it, respectively. ;

[0068] is the primary excitation admittance of PT;

[0069] , They are the primary voltage and current of PT respectively;

[0070] , They are the secondary voltage and current converted to the primary end respectively;

[0071] is the PT primary excitation current.

[0072] The mathematical model of PT error is established based on circuit theory: According to the principle of subtractive polarity, the reference directions of voltage and current are defined as shown in Figure 2, and the voltage error of the PT output terminal relative to the input terminal is:

[0073]

[0074] Its relative error:

[0075]

[0076] This is the sum of two complex numbers, representing the no-load complex error and the loaded complex error respectively. That is, the PT complex error when the secondary circuit is open and the admittance is zero, which is related to the PT material and structural parameters and is a fixed value after the PT is manufactured; while the load complex error It is related to the on-site application conditions, that is, it is related to the inductance, capacitance and size of the load. It is a variable error and an application error.

[0077] Express the above formula using complex polar coordinates and rectangular coordinates respectively, then:

[0078] No-load complex error:

[0079] Load complex error:

[0080] Synthetic complex error:

[0081] Where:

[0082] It is the short-circuit impedance of the PT secondary terminal converted to the primary terminal (secondary short circuit);

[0083] It is the short-circuit impedance converted from the primary end of the PT to the secondary end (primary short circuit);

[0084] for Converted to the equivalent leakage impedance of the secondary;

[0085] They are the leakage impedance angle, short-circuit impedance angle and secondary load impedance angle of the PT primary winding;

[0086] is the hysteresis angle of the PT core, i.e. the loss angle, which is inductive. >0;

[0087] They are PT no-load complex error, load complex error, and synthetic complex error respectively;

[0088] are the modulus of PT no-load complex error and loaded complex error respectively;

[0089] are the real parts of each complex error, corresponding to the ratio difference of PT no-load, load and composite errors;

[0090] are the imaginary parts of each complex error, corresponding to the angular difference of PT no-load, load, and composite error;

[0091] They are the PT primary winding excitation admittance and secondary load admittance respectively.

[0092] Example 1

[0093] The mathematical model of electric energy metering error caused by PT ratio difference and angle difference is:

[0094] Three-phase four-wire energy measurement:

[0095] ;

[0096] Three-phase three-wire energy measurement: .

[0097] It can be seen that the electric energy metering error caused by PT is composed of the electric energy error component caused by PT ratio difference and the electric energy error component caused by PT angle difference. Based on the above error relationship, the influence of PT error can be reduced by adjusting the ratio difference, angle difference or polarity.

[0098] When the line is operating normally, the load power factor is close to 1. The value is very small, so for the three-phase four-wire power metering system, the power error caused by the PT angle difference accounts for a small proportion, and the power error caused by the PT ratio difference accounts for a large proportion. Based on this, by adjusting The coefficient of the angular difference, that is, the angular difference, makes the angular difference ratio high and the corresponding ratio ratio small, which can effectively reduce the three-phase four-wire electric energy metering error; and for the three-phase three-wire electric energy metering system, by adjusting the two-phase PT ratio difference to make the positive and negative different and the angular difference the same, the algebraic sum of the electric energy error can be minimized, thereby reducing the three-phase three-wire electric energy metering error.

[0099] To this end, this embodiment provides an electromagnetic current transformer error optimization analysis method, based on which the CT ratio difference and angle difference are optimized and adjusted to minimize the algebraic value of the electric energy error, including the following steps:

[0100] Step 1: Express the PT load error characteristics as a complex number. The corresponding polar coordinate and rectangular coordinate expressions are: ;

[0101] in, is the PT load complex error, is the modulus of the PT load complex error; They are the PT secondary circuit load admittance and the impedance angle corresponding to the admittance; They are the PT primary short-circuit converted impedance and the corresponding impedance angle; Admittance , short circuit impedance Model; They are the ratio difference and angle difference of PT load error respectively;

[0102] In the complex plane rectangular coordinate system, according to the load characteristics, the load complex error vector distribution area can be used Figure 3 A complex error vector circle is represented by a circle with a diameter equal to , secondary circuit admittance value Size determines the size of the circle;

[0103] According to the load impedance angle range of -90°~90°, the PT load complex error is distributed in ~ The 180° semicircular sector area includes quadrants II, III, and IV;

[0104] The 1 / 2 dividing line of the semicircular sector corresponds to the impedance angle =0, that is, the complex error vector of pure resistive load; within the 90° counterclockwise direction of the dividing line is the inductive load complex error area, accounting for 1 / 2 of the semicircle, including quadrants III and II; within the 90° clockwise direction of the dividing line is the capacitive load complex error area, accounting for 1 / 2 of the semicircle, including quadrants III and IV.

[0105] Step 2: Based on the complex error vector circle, the PT load error and synthetic error characteristics can be analyzed intuitively and graphically:

[0106] Perform equivalent transformation of the load complex error step by step:

[0107]

[0108] in Defined as the unit load complex error, corresponding to unit impedance That is, the admittance value is 1 and the impedance angle is The load complex error, that is, the PT load complex error It is the product of the PT load admittance value and the unit load complex error;

[0109] The actual load complex error vector circle is an enlarged or reduced version of the unit load complex error vector circle. The size of the vector circle determines the size of the ratio difference and the angular difference. The distribution characteristics of the unit load complex error vector circle determine the positive and negative of the ratio difference and the angular difference and their distribution ratio in the same circle. Figure 3 In the figure, the two circles of corresponding size are the load complex error vector circles , unit complex error vector circle .

[0110] Based on the complex plane rectangular coordinate system, the ratio difference and angle difference correspond to the rectangular coordinates , The projection on the axis, the length of the projection corresponds to the size of the corresponding ratio difference and angular difference, and the positioning of the quadrant of the complex error determines the positive and negative of the ratio difference and angular difference.

[0111] Complex error vector circle based on unit load:

[0112] For resistive loads, the impedance angle =0°, the complex error vector is in the third quadrant, corresponding to the dividing line of the semicircular sector area, that is, the dividing line between the inductive load error and the capacitive load error area; the PT ratio difference and angle difference are always negative and are both constant values;

[0113] For inductive loads, From 0 to 90° in the clockwise direction, the complex error vector is distributed in quadrants III and II, the PT ratio difference is always negative, and the ratio difference changes from "small negative → large negative → maximum negative → small negative", and the maximum ratio difference corresponds to the impedance angle ,and Axis coincidence; PT angle difference can be positive or negative, is the dividing point between positive and negative angle difference, Less than Negative, greater than is positive; the angular difference changes monotonically from “negative large → negative small → 0 → positive small → positive large”, that is, the algebraic value changes monotonically from small to large; Figure 5 This is a graph showing the relationship between the corresponding ratio difference and angle difference as the impedance angle changes.

[0114] For capacitive loads, From 0 to -90° in the counterclockwise direction, the complex error vector is distributed in quadrants III and IV, the PT angle difference is always negative, and the angle difference changes from "small negative → large negative → maximum negative → small negative", and the maximum angle difference corresponds to the impedance angle ,and Axis coincidence; PT ratio difference can be positive or negative, is the dividing point between positive and negative ratio difference, Greater than The ratio difference is negative, less than The ratio difference is positive; the ratio difference value changes monotonically from “negative large → negative small → 0 → positive small → positive large”, that is, the algebraic value changes monotonically from small to large. Figure 5 This is a graph showing the relationship between the corresponding ratio difference and angle difference as the impedance angle changes.

[0115] The PT no-load complex error is equivalent to a fixed value inductive load complex error, and the corresponding ratio difference is , the angular difference is , then the ratio difference and angular difference of the synthetic complex error can be regarded as the result of the ratio difference and angular difference of the load complex error after the displacement of the origin of the coordinate system. The coordinate value of the origin movement is , then the synthetic complex error vector circle is an eccentric circle, and the variation law of the ratio difference and angle difference of the synthetic complex error is the same as that of the load complex error, such as Figure 4 As shown in the figure, the center of the synthetic complex error vector circle moves within the vector circle with the no-load error magnitude and vector direction. Usually, the quadrant of the synthetic complex error distribution remains unchanged, but the areas of quadrants III and IV are reduced, and the proportion of quadrant II increases; the inductive load angular difference increases in the positive direction and the ratio difference increases in the negative direction, while the capacitive load angular difference and ratio difference decrease.

[0116] For the synthetic complex error:

[0117]

[0118] The magnitude of the vector circle from the origin is:

[0119]

[0120] The error margins of resistance, inductance, and capacitance are:

[0121]

[0122] Where: They are the error amplitudes corresponding to pure resistance, pure inductance, and pure capacitance loads, that is, the error boundaries of each load characteristic.

[0123] The variation rules of ratio difference and angle difference of synthetic complex error are the same as those of load complex error.

[0124] Step 3: Based on the error relationship shown in the complex error vector circle diagram, the PT load impedance angle is adjusted to minimize the algebraic sum of the ratio difference / angle difference of the three-phase PT complex errors:

[0125] 3.1) For the PTs that make up the three-phase four-wire electric energy metering device, when the ratio differences of the three-phase PTs are all of the same sign, adjust the respective complex error vectors to The axes are brought closer together, so that the ratio difference tends to 0, and thus the algebraic sum of the three-phase ratio differences tends to 0; when the ratio differences of the three-phase PTs are not all of the same sign, fix one phase and adjust the complex error impedance angles of the other two phases: make the ratio difference of the complex error of one phase equal to the fixed ratio difference in polarity, and the complex error of the other phase tends to The axis approach ratio difference tends to 0, and finally the algebraic sum of the three ratio differences tends to 0;

[0126] For the three-phase three-wire electric energy metering device PT, when the ratio difference of the two-phase PT is the same, adjust the respective complex error vectors to When the axes are close to each other, the angle difference is of the same sign, the ratio difference tends to 0, and thus the algebraic sum of the two phase differences tends to 0; when the ratio difference of the two-phase PT is not of the same sign, fix one phase and adjust the complex error impedance angle of the other phase to make the ratio difference polarity equal to the fixed ratio difference, so that the sum of the two phase differences is equal to 0 and the angle difference is relatively reduced, or adjust the complex error impedance angle of the other phase to be the same as the angle difference of the fixed phase, so that the difference of the two phase angle differences is equal to 0 and the sum of the ratio differences is relatively reduced.

[0127] Example 2

[0128] An electromagnetic voltage transformer error optimization analysis method optimizes and adjusts PT ratio difference and angle difference to minimize the algebraic value of electric energy error, including the following steps:

[0129] Step 1: Express the PT load error characteristics as a complex number. The corresponding polar coordinate and rectangular coordinate expressions are: ;

[0130] in, is the PT load complex error, is the modulus of the PT load complex error; are the ratio difference and angle difference of PT error respectively; They are the PT secondary circuit load admittance and the impedance angle corresponding to the admittance; They are the PT primary short-circuit converted impedance and the corresponding impedance angle; Admittance , short circuit impedance Model;

[0131] In the complex plane rectangular coordinate system, according to the load characteristics, the load complex error vector distribution area is represented by a complex error vector circle, and the diameter of the circle is equal to , secondary circuit admittance value Size determines the size of the circle;

[0132] Step 2, perform intuitive graphical analysis of PT load error and synthetic error characteristics based on the complex error vector circle;

[0133] Step 3, based on the error relationship shown in the complex error vector circle diagram, by adjusting the PT load impedance angle, the algebraic sum of the ratio difference / angle difference of the three-phase PT complex errors constituting the electric energy metering device is minimized.

[0134] In step 3, it also includes:

[0135] 3.2) Impedance angle adjustment calculation

[0136] a) Knowing the synthetic complex error and no-load error, adjust the error vector circle Impedance angle calculation for close axes

[0137]

[0138] b) Knowing the synthetic complex error and no-load error, adjusting the difference between the fixed complex error and the fixed complex error Calculation of impedance angles that are different and equal

[0139]

[0140] Respectively represent the composite ratio difference, angle difference and corresponding no-load ratio, angle difference and load ratio, angle difference values ​​to be adjusted; are the adjusted / reference ratio differences, respectively; They are the leakage impedance angle, short-circuit impedance angle, and core hysteresis loss angle of the PT primary winding respectively; is the adjusted target impedance angle.

[0141] 3.3) Impedance angle adjustment and parameter calculation

[0142] a) Negative adjustment and calculation of impedance angle

[0143] For PT secondary resistive load, connect capacitor in series:

[0144]

[0145] That is, the secondary resistive load of the PT A capacitor in series is or capacitive reactance equals Capacitance;

[0146] Connect capacitor in series with PT secondary inductive load:

[0147]

[0148] That is, the secondary inductive load of PT A compensation capacitor is connected in series or Capacitive Reactance Capacitance;

[0149] Connect compensation capacitor in series with PT secondary capacitive load:

[0150]

[0151] That is, the secondary capacitive load of PT A compensation capacitor is connected in series. or capacitive reactance equals of capacitance.

[0152] b) Positive adjustment and calculation of impedance angle

[0153] For the PT secondary capacitive load, connect the compensation inductor in series:

[0154]

[0155] That is, the secondary capacitive load of PT A compensation inductor is connected in series. or inductive reactance equals inductor components.

[0156] In the above formula: They are the PT secondary inductive and capacitive load impedance and the corresponding resistance value, inductive reactance value / compensated inductive reactance value, and capacitive reactance value / compensated capacitive reactance value; They are respectively the compensation capacitance value, inductance value, and PT working voltage power frequency value.

[0157] In short, the above adjustment rules can adapt to most line operating conditions, greatly reduce the error of electric energy metering, and ensure that the electric energy data measured by the electric energy metering device is true and reliable.

[0158] The above implementation modes are not limitations of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the scope of the technical solution of the present invention also belong to the protection scope of the present invention.

Claims

1. An electromagnetic voltage transformer error optimization analysis method, characterized in that: The following steps are involved: Step 1: Express the PT load error characteristics as a complex number. The corresponding polar coordinate and rectangular coordinate expressions are: ; in, is the PT load complex error, is the modulus of the PT load complex error; They are the PT secondary circuit load admittance and the impedance angle corresponding to the admittance; They are the PT primary short-circuit converted impedance and the corresponding impedance angle; Admittance , short circuit impedance Model; They are the ratio difference and angle difference of PT load error respectively; In the complex plane rectangular coordinate system, according to the load characteristics, the load complex error vector distribution area is represented by a complex error vector circle, and the diameter of the circle is equal to , secondary circuit admittance value Size determines the size of the circle; Step 2, perform intuitive graphical analysis of PT load error and synthetic error characteristics based on the complex error vector circle; Step 3, based on the error relationship shown in the complex error vector circle diagram, by adjusting the PT load impedance angle, the algebraic sum of the ratio difference / angle difference of the three-phase PT complex errors constituting the electric energy metering device is minimized.

2. The electromagnetic voltage transformer error optimization analysis method according to claim 1, characterized in that: In step 1, according to the load impedance angle range of -90°~90°, the PT load complex error is distributed in ~ The 180° semicircular sector area includes quadrants II, III, and IV; The 1 / 2 dividing line of the semicircular sector corresponds to the impedance angle =0, that is, the complex error vector of pure resistive load; within the 90° clockwise direction of the dividing line is the inductive load complex error area, accounting for 1 / 2 of the semicircle, including quadrants III and II; within the 90° counterclockwise direction of the dividing line is the capacitive load complex error area, accounting for 1 / 2 of the semicircle, including quadrants III and IV.

3. The electromagnetic voltage transformer error optimization analysis method according to claim 1, characterized in that: In step 2, the load complex error is equivalently transformed: ； in Defined as the unit load complex error, corresponding to unit impedance That is, the admittance value is 1 and the impedance angle is The load complex error, that is, the PT load complex error It is the product of the PT load admittance value and the unit load complex error; Complex error vector circle based on unit load: For resistive loads, the impedance angle =0°, the complex error vector is in the third quadrant, corresponding to the dividing line of the semicircular sector area, that is, the dividing line between the inductive load error and the capacitive load error area; the PT ratio difference and angle difference are always negative and are both constant values; For inductive loads, From 0 to 90° in the clockwise direction, the complex error vector is distributed in quadrants III and II, the PT ratio difference is always negative, and the ratio difference changes from "small negative → large negative → maximum negative → small negative", and the maximum ratio difference corresponds to the impedance angle ,and Axis coincidence; PT angle difference can be positive or negative, is the dividing point between positive and negative angle difference, Less than Negative, greater than is positive; the angular difference changes monotonically from "negative large → negative small → 0 → positive small → positive large", that is, the algebraic value changes monotonically from small to large; For capacitive loads, From 0 to -90° in the counterclockwise direction, the complex error vector is distributed in quadrants III and IV, the PT angle difference is always negative, and the angle difference changes from "small negative → large negative → maximum negative → small negative", and the maximum angle difference corresponds to the impedance angle ,and Axis coincidence; PT ratio difference can be positive or negative, is the dividing point between positive and negative ratio difference, Greater than The ratio difference is negative, less than The ratio difference is positive; the ratio difference value changes monotonically from "negative large → negative small → 0 → positive small → positive large", that is, the algebraic value changes monotonically from small to large.

4. The electromagnetic voltage transformer error optimization analysis method according to claim 1, characterized in that: In step 2, the PT no-load complex error is equivalent to a fixed value inductive load complex error, and the corresponding ratio difference is , the angular difference is , then the ratio difference and angular difference of the synthetic complex error can be regarded as the result of the ratio difference and angular difference of the load complex error after the displacement of the origin of the coordinate system. The coordinate value of the origin movement is , then the synthetic complex error vector circle is an eccentric circle, and the variation law of the ratio difference and angle difference of the synthetic complex error is the same as that of the load complex error; For the synthetic complex error: ； The magnitude of the vector circle from the origin is: ； The error margins of resistance, inductance, and capacitance are: ； They are the error amplitudes corresponding to pure resistance, pure inductance, and pure capacitance loads, that is, the error boundaries of each load characteristic.

5. The electromagnetic voltage transformer error optimization analysis method according to claim 1, characterized in that: In step 3, for the PTs constituting the three-phase four-wire electric energy metering device, when the ratio differences of the three-phase PTs are all of the same sign, adjust the respective complex error vectors to The axes are brought closer together, so that the ratio difference tends to 0, and thus the algebraic sum of the three-phase ratio differences tends to 0; when the ratio differences of the three-phase PTs are not all of the same sign, fix one phase and adjust the complex error impedance angles of the other two phases so that the ratio difference of the complex error of one phase is equal to the fixed ratio difference in polarity, and the complex error of the other phase is equal to As the axes approach each other, the ratio difference tends to 0, and finally the algebraic sum of the three ratio differences tends to 0.

6. The electromagnetic voltage transformer error optimization analysis method according to claim 1, characterized in that: In step 3, for the three-phase three-wire electric energy metering device PT, when the ratio differences of the two-phase PTs are of the same sign, adjust the respective complex error vectors to When the axes are close to each other, the angle difference is of the same sign, the ratio difference tends to 0, and thus the algebraic sum of the two phase differences tends to 0; when the ratio difference of the two-phase PT is not of the same sign, fix one phase and adjust the complex error impedance angle of the other phase to make the ratio difference polarity equal to the fixed ratio difference, so that the sum of the two phase differences is equal to 0 and the angle difference is relatively reduced, or adjust the complex error impedance angle of the other phase to be the same as the angle difference of the fixed phase, so that the difference of the two phase angle differences is equal to 0 and the sum of the ratio differences is relatively reduced.

7. The electromagnetic voltage transformer error optimization analysis method according to claim 1, characterized in that: In step 3, the impedance angle is calculated, including: a) Knowing the synthetic complex error and no-load error, adjust the error vector circle Impedance angle calculation for close axes ； b) Knowing the synthetic complex error and no-load error, adjusting the difference between the fixed complex error and the fixed complex error Calculation of impedance angles that are different and equal ； Respectively represent the composite ratio difference, angle difference and corresponding no-load ratio, angle difference and load ratio, angle difference values ​​to be adjusted; are the adjusted / reference ratio differences, respectively; They are the leakage impedance angle, short-circuit impedance angle, and core hysteresis loss angle of the PT primary winding respectively; is the adjusted target impedance angle.

8. The electromagnetic voltage transformer error optimization analysis method according to claim 7, characterized in that: In step 3, the impedance angle is adjusted and parameter calculations are performed, including: a) Negative adjustment and calculation of impedance angle For PT secondary resistive load, connect capacitor in series: ； That is, the secondary resistive load of the PT A capacitor in series is or capacitive reactance equals Capacitance; Connect capacitor in series with PT secondary inductive load: ； That is, the secondary inductive load of PT A compensation capacitor is connected in series or Capacitive Reactance Capacitance; Connect compensation capacitor in series with PT secondary capacitive load: ； That is, the secondary capacitive load of PT A compensation capacitor is connected in series. or capacitive reactance equals Capacitance.

9. The electromagnetic voltage transformer error optimization analysis method according to claim 7, characterized in that: In step 3, b) impedance angle forward adjustment and calculation: For the PT secondary capacitive load, connect the compensation inductor in series: ； That is, the secondary capacitive load of PT A compensation inductor is connected in series. or inductive reactance equals Inductor components; They are the PT secondary inductive and capacitive load impedance and the corresponding resistance value, inductive reactance value / compensated inductive reactance value, and capacitive reactance value / compensated capacitive reactance value; They are respectively the compensation capacitance value, inductance value, and CPT working voltage power frequency value.

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